Replacement for a RF Transistor

Discussion in 'Wireless & RF Design' started by nblasco, Aug 11, 2018.

  1. nblasco

    Thread Starter New Member

    Aug 11, 2018
    Hello, I am trying to make a simple FM transmitter, but I have a problem, the transistor 2N3563 used here is not easily available in my city.
    I´m looking for a equivalent transitor, because I already have all the other materials to make this.
    Thanks you for the help!
  2. dl324

    AAC Fanatic!

    Mar 30, 2015
  3. DickCappels


    Aug 21, 2008
    Most modern small signal NPN transistors will work in that circuit. 2N3904, 2N4401, 2NANYTHING :)
  4. Bordodynov

    Well-Known Member

    May 20, 2015
  5. Dodgydave

    AAC Fanatic!

    Jun 22, 2012

    NTE108 replacement.
  6. nblasco

    Thread Starter New Member

    Aug 11, 2018
    Thank you all for replying, I tried some of the ones I had searched on Google but I realized that it depended on the circuit which was going to be compatible, that's why I post my question here.
    I'm going to try the NTE108 and the 2N's family.
    Greetings to everyone
  7. Audioguru


    Dec 20, 2007
    That circuit is so simple that it will have poor performance:
    1) All FM radio stations use pre-emphasis which boosts treble audio frequencies and all FM radios have the corresponding de-emphasis that cuts the boost down to normal and cuts hiss. Since your simple transmitter has no pre-emphasis then audio from it heard on a normal FM radio will have its treble audio frequencies cut and will sound muffled.

    2) Since your antenna connects to the tuned LC circuit then the radio frequency will change if something moves towards or away from the antenna.

    3) If you use a battery then the radio frequency will change as the battery voltage runs down.

    My FM transmitter uses ordinary 2N3904 transistors and does not have these problems because it has pre-emphasis that sounds great, it has an RF amplifier to isolate the oscillator from the antenna and it has a low dropout voltage regulator: